CHAPTER V. ANATOMY AND PHYSIOLOGY IN THE NINETEENTH CENTURY
 Baron de Cuvier's Theory of the Earth. New York, 1818, p. 123.
 On the Organs and Mode of Fecundation of Orchidex and Asclepiadea, by Robert Brown, Esq., in Miscellaneous Botanical Works. London, 1866, Vol. I., pp. 511-514.
 Justin Liebig, Animal Chemistry. London, 1843, p. 17f.
CHAPTER VI. THEORIES OF ORGANIC EVOLUTION
 "Essay on the Metamorphoses of Plants," by Goethe, translated for the present work from Grundriss einer Geschichte der Naturwissenschaften, by Friederich Dannemann (2 vols.). Leipzig, 1896, Vol. I., p. 194.
 The Temple of Nature, or The Origin of Society, by Erasmus Darwin, edition published in 1807, p. 35.
 Baron de Cuvier, Theory of the Earth. New York, 1818, p.74. (This was the introduction to Cuvier's great work.)